Acids & Bases Problem Set

Question 7: Neutralizing a basic solution

How many ml of a 0.4 M HCl solution are required to bring the pH of 10 ml of a 0.4 M NaOH solution to 7.0 (neutral pH)?

Note: HCl and NaOH both completely dissociate in water (i.e., no pKa calculation is necessary).

A.

4

B.

40

C.

10

D.

20

E.

2

Tutorial

Neutralizing a basic solution

This question does not require any complicated calculations, but rather can be solved by considering how acids and bases work. In this case, both the acid and the base solutions are at the same concentration. Also, as noted in the question itself, NaOH and HCl completely dissociate.

Thus, a neutral pH can be achieved by adding an equal amount of the acid solution to the base solution.